By Kevin Scheiwiller of Citizens for Conservation
As many practitioners know, wetlands can be one of the most frustrating and resource demanding areas to restore. Countless wetland plantings have shown a large flush in native diversity in the first few years just to be overrun by the seed bank of the “wetland thugs;” cattails, reed canary grass, and phragmites. At Citizens for Conservation, we had left most of our wetlands alone for this reason. That was until we enlisted the help of the warrior sedges.
Who are the warrior sedges? These 10 species of Carex were hand selected based on their tendency to be able to withstand invasion by the wetland thugs in the few remaining local remnant wetlands. They are all highly rhizomatous species, that when planted in a focused manner can create a tight native matrix strong enough to keep out the invasion of the wetland thugs.
So what? Why replace one monoculture with another? We have found that while these warrior sedge matrices are dense enough to keep out the thugs, they are not inhibiting the growth of other native wetland species such as Sneezeweed, Monkey Flower, Mad-Dog Skullcap, Blue Flag Iris, and others. All these wetland associates have coevolved for millennia and still seem to understand how to grow together.
The hardened restoration ecologist will wonder how long this wetland planting will keep out the wetland thugs. Time will be the true test, but after a decade of using this technique we have been able to reclaim pothole wetlands and a long stretch of streambank. All of which requires a very small amount of maintenance after year three of this method.
For a detailed explanation of the process see “The Way of the Warriors.” https://www.nachusagrasslands.org/uploads/5/8/4/6/58466593/the_way_of_the_warriors.pdf
Really good information on the thugs and what species can hold their own. Lacustris certainly is one that stands out from my experience. Another which held up over time in my own saturated RCG acreage is Blue joint grass. Although not as tall and not as much in standing water it withstood the assaults and although there was some RCG intermixed with it held on for all those years when no one did anything. Mike Jones pointed out to me that it needed fire to go to seed and managed to get it to burn tow ears in a row and we got seed! Getting these areas to burn is quite the challenge and I am leaning towards trying to get burns done anytime it dries out as no chance this year as just too wet and usually much wetter in the spring. Removing vast blankets of RCG only makes it wetter!
I am not clear on the photosensitive nature of Clethodim except what I have read. Craig Annen’s posts on the topic indicated just the opposite and my understanding is that Clethodim loses 50% effectiveness if exposed to sunlight. In his paper titled “guidelines for electing Herbicide additive for Reed Canary grass control he states the following. Do you have new information on this topic? This is part of the reason I went to DX (fluaziflop). More expensive however. The needle we are trying to thread with the grass selectives and standing water is narrow as it would be ideal to use grass selective with the sedges but rare that it is not wet???
“Another field condition to consider when applying grass specific herbicides of the cyclohexane-1,3-dione chemical family (herbicides with common names ending in –dim: sethoxydim and clethodim) is ultraviolet radiation. Ultraviolet light decomposes this class of herbicides. Tenminute exposure to ultraviolet light has been found to degrade more than 50% of sethoxydim applied to leaf surfaces (Shoaf and Carlson 1992). Consider this: The uptake period for sethoxydim is about one hour. If you apply sethoxydim on a bright, sunny day during the early afternoon (when ultraviolet levels are high), you may be loosing most of the active ingredient to decomposition before it even enters the plant. To minimize degradation by ultraviolet light, apply grass-specific herbicides on cloudy days, or apply them in either mid-morning (after dew has evaporated from leaves) or late afternoon, when ultraviolet levels are lower. Ultraviolet light will also reduce the effectiveness of vegetable-based crop oils. Methylated vegetable oils are slightly more resistant to ultraviolet degradation (Matysiak and Nalewaja 1999) and can be used in place of ordinary crop oils if ultraviolet light levels are a concern. Grass-specific herbicides belonging to the aryloxyphenoxypropionic acid (APP) chemical family (herbicides with common names ending in –fop: fluazifop and quizalofop) are not decomposed by ultraviolet light (at least not at levels we are likely to encounter in the field) because of their chemical structure.
So do you mean that the sedges are used as a barrier between existing cattails for example and native plantings that you’ve installed? Or are you putting them everywhere the area that you want to cover with natives in the long term? Thanks.
We use these sedges everywhere that we are trying to restore marsh and sedge meadows in the long term. A similar analogy would be early prairie restorations using bunch grasses like Big Blue and Indian Grass to establish a native matrix before seeding in conservatives. One of the big differences is that these warrior sedges do not seem to be as aggressive as bunch grass and allow other sedge meadow species to thrive.
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How do you source your sedge plugs? Have you tried harvesting sedge “plugs” from healthy stands?
Great question! We are always limited by the number of plugs that we are able purchase each year. This is no cheap venture.
Last year we were able to “rescue” some Cx lacustris from the side of a roadway that was being expanded. We took these clumps of sedges and divided them out into individual plugs. This seemed to work really well, and allowed us to turn one clump into 100 new sedge starts. We have yet to harvest from any established sedge colonies in previously planted areas, but I think that is the right approach. If we dig one clump up, it should fill back in and then that one clump can be turned into 100 new sedges. We will try it out this year and get back to you on the results!
Any experience on the optimal time of year for harvesting Cx plugs? I’d guess there’s a slight preference for spring.
Spring is definitely the best time, even starting in another week or two. We will divide them, and put them in plug trays around the first week of April. By late May, early June they have already started to fill out the cell and become plant-able!